From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 499BBC4338F for ; Mon, 2 Aug 2021 14:22:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2CF0660EC0 for ; Mon, 2 Aug 2021 14:22:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235900AbhHBOWo (ORCPT ); Mon, 2 Aug 2021 10:22:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45974 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235963AbhHBOWj (ORCPT ); Mon, 2 Aug 2021 10:22:39 -0400 Received: from mail-pl1-x62e.google.com (mail-pl1-x62e.google.com [IPv6:2607:f8b0:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 412A2C0701F8; Mon, 2 Aug 2021 07:09:00 -0700 (PDT) Received: by mail-pl1-x62e.google.com with SMTP id t3so17633081plg.9; Mon, 02 Aug 2021 07:09:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=/cdM8HpdDM3Yh7GGE7exLVKVMbD9iA/9tyiszM+STgg=; b=EyGzIbCm/4WfGRl2TIpRtI8exR5hEZdzfziWgkyJF2rPPiSQ75H+98IAopMmYevfFk Ov/fJ43JIQnILsE3s/0qzNMc0nrf6uUXE2j26BExy5g7B3BpTmvtolJxygg5zsp4OzjQ /7pE2ruUo+gM4LDOxH4S0QCLE3cZn8HjYiXLd7zaPCzN5tcqN75mDO2ycYHk5nf3h82W fzBmyU3qV/42PwBr8KexEQmrjqnx6SCVYEPtgGSjDXNVb1Uffuv26Hb9ID8hcdFyzcOI 2ZeoAyGM+UdW1S66kVSqZMjoR5QEIes/nzm112DtVAisubEuzui0RUvnkB/UUMAP1zyE JLjQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=/cdM8HpdDM3Yh7GGE7exLVKVMbD9iA/9tyiszM+STgg=; b=KCWguRI6XpOC4NANbUmdJU8A2dKRuK8R8fYdNL+T/y2i5pq1CEhNeHe45HxKcHKw7Z 86ge4xwUvuutP+xU1LxjDEeMvvNjEsVWu2kVa3U1QxxpQMMqARf+5y4M5fp/khkhQT23 WayH5FKCOBE0JERAK67O8grW/MY7MUbLdbbWxBbVYcVSUcyh3kvrpJ027G0GPXcFrgJd UpAq0gShQ9irj3syRYMy17jpzm0mTlxc4mw7VdyGEl2MeNxeiaz/fntlkl+o3aK2BXvW IafCL2rZu5XdS8ynS5ivAMw16b68P7ejnCqw++4vWtdbqJ+rzfAWUBmbl4xjDMNqrhOw FRkw== X-Gm-Message-State: AOAM531p54V5x9dsA35BewNi8pOllVsm8IvlHH0EVAzNGznsHIXa1fAx kOnx+1AHhY0DeljgNcI3H8g= X-Google-Smtp-Source: ABdhPJz9/oIt1d6cc74gFPmQ4IHl6g1R2CxfQ4Ko9VZ15V7BmdIE77nzkycqmmDE/JgZuYIJykKPEQ== X-Received: by 2002:aa7:8148:0:b029:31b:10b4:f391 with SMTP id d8-20020aa781480000b029031b10b4f391mr16506898pfn.69.1627913339735; Mon, 02 Aug 2021 07:08:59 -0700 (PDT) Received: from ?IPv6:2404:f801:0:5:8000::4b1? ([2404:f801:9000:18:efec::4b1]) by smtp.gmail.com with ESMTPSA id fz10sm11071046pjb.40.2021.08.02.07.08.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Aug 2021 07:08:59 -0700 (PDT) Subject: Re: [PATCH 13/13] HV/Storvsc: Add Isolation VM support for storvsc driver To: Joerg Roedel Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, will@kernel.org, davem@davemloft.net, kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com, arnd@arndb.de, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, thomas.lendacky@amd.com, brijesh.singh@amd.com, ardb@kernel.org, Tianyu.Lan@microsoft.com, rientjes@google.com, martin.b.radev@gmail.com, akpm@linux-foundation.org, rppt@kernel.org, kirill.shutemov@linux.intel.com, aneesh.kumar@linux.ibm.com, krish.sadhukhan@oracle.com, saravanand@fb.com, xen-devel@lists.xenproject.org, pgonda@google.com, david@redhat.com, keescook@chromium.org, hannes@cmpxchg.org, sfr@canb.auug.org.au, michael.h.kelley@microsoft.com, iommu@lists.linux-foundation.org, linux-arch@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, netdev@vger.kernel.org, vkuznets@redhat.com, anparri@microsoft.com References: <20210728145232.285861-1-ltykernel@gmail.com> <20210728145232.285861-14-ltykernel@gmail.com> From: Tianyu Lan Message-ID: Date: Mon, 2 Aug 2021 22:08:43 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On 8/2/2021 9:20 PM, Joerg Roedel wrote: > On Wed, Jul 28, 2021 at 10:52:28AM -0400, Tianyu Lan wrote: >> In Isolation VM, all shared memory with host needs to mark visible >> to host via hvcall. vmbus_establish_gpadl() has already done it for >> storvsc rx/tx ring buffer. The page buffer used by vmbus_sendpacket_ >> mpb_desc() still need to handle. Use DMA API to map/umap these >> memory during sending/receiving packet and Hyper-V DMA ops callback >> will use swiotlb function to allocate bounce buffer and copy data >> from/to bounce buffer. > > I am wondering why you dont't use DMA-API unconditionally? It provides > enough abstraction to do the right thing for isolated and legacy VMs. > In VMbus, there is already a similar bounce buffer design and so there is no need to call DMA-API for such buffer. Calling DMA-API is to use swiotlb bounce buffer for those buffer which hasn't been covered. This is why need to conditionally call DMA API.